1. Field of the Invention
The present invention relates to a device for forming a headrest. In particular, the invention is directed to a device for automatically forming a headrest, which is provided with a foaming die and designed to automatically inject a liquid foaming agent into a trim cover assembly placed in the foaming die and cure the liquid foaming agent into an increased mass of foam padding integrally filled in the trim cover assembly, thereby producing a resultant headrest.
2. Description of Prior Art
In general, a conventional foaming process for forming a headrest by means of a foaming die unit requires the steps of: providing a preformed three-dimensional trim cover assembly of a configuration conforming to a contour of headrest, with a headrest stay attached thereto; placing such trim cover assembly with the headrest stay in the foaming die; then inserting an injection nozzle into the trim cover assembly; injecting a liquid foaming agent via that injection nozzle into the inside of the trim cover assembly; and curing the liquid foaming agent into an increased mass of foam padding filled in the trim cover assembly together with the headrest stay in an integral manner.
The aforementioned foaming process has a problem that the increasing mass of foam padding or foamed material is forced into the injection nozzle during the foaming operation and eventually discharged from that injection nozzle to the outside of the die.
Hitherto, in order to prevent such undesired discharge of foamed material, the foaming die unit is provided with a movable lid for the hole of the injection nozzle closed, and such lid must be manually retained by a worker in a state pressed against the injection nozzle to keep closing the hole of injection nozzle, as for example disclosed from the Japanese Patent No. 3650860.
In other words, it has been required on the worker's side to keep pressing the lid against the hole of injection nozzle for a predetermined period of time until the liquid foaming agent is cured into a final mass of foam padding in the trim cover assembly.
But, in mass production of headrests, during the time for curing the liquid foaming agent, another foaming die containing a trim cover assembly and headrest stay therein is transferred to the worker for the above-described liquid foaming agent injection operation, and therefore, the worker must stop such another foaming die until the liquid foaming agent is cured in the first foaming die, while the worker has to be ready to insert an injection gun to the hole of the injection nozzle provided on that another foaming die. Thus, the conventional headrest production system of this kind takes much time at the steps where the worker keeps closing the hole of the injection nozzle and thereafter inserts an injection gun to an injection nozzle of the next foaming die.